Likely Additive Ergogenic Effects of Combined Preexercise Dietary Nitrate and Caffeine Ingestion in Trained Cyclists

Abstract

Aims . To evaluate the possible additive effects of beetroot juice plus caffeine on exercise performance. Methods . In a randomized, double-blinded study design, fourteen healthy well-trained men aged 22 ± 3 years performed four trials on different occasions following preexercise ingestion of placebo (PLA), PLA plus 5 mg/kg caffeine (PLA+C), beetroot juice providing 8 mmol of nitrate (BR), and beetroot juice plus caffeine (BR+C). Participants cycled at 60% maximal oxygen uptake ( V ˙ O 2 max) for 30 min followed by a time to exhaustion (TTE) trial at 80% V ˙ O 2 max. Saliva was collected before supplement ingestion, before exercise, and after the TTE trial for salivary nitrate, nitrite, and cortisol analysis. Results . In beetroot trials, saliva nitrate and nitrite increased >10-fold before exercise compared with preingestion ( P ≤ 0.002 ). TTE in BR+C was 46% higher than in PLA ( P = 0.096 ) and 18% and 27% nonsignificant TTE improvements were observed on BR+C compared with BR and PLA+C alone, respectively. Lower ratings of perceived exertion during TTE were found during 80% V ˙ O 2 max on BR+C compared with PLA and PLA+C ( P < 0.05 for both). Conclusions . Acute preexercise beetroot juice coingestion with caffeine likely has additive effects on exercise performance compared with either beetroot or caffeine alone.